@article {853, title = {Cost-Efficient RSSI-Based Indoor Proximity Positioning, for Large/Complex Museum Exhibition Spaces}, journal = {Sensors}, volume = {25}, year = {2025}, pages = {2713}, abstract = {

RSSI-based proximity positioning is a well-established technique for indoor localization, featuring simplicity and cost-effectiveness, requiring low-price and off-the-shelf hardware. However, it suffers from low accuracy (in NLOS traffic), noise, and multipath fading issues. In large complex spaces, such as museums, where heavy visitor traffic is expected to seriously impact the ability to maintain LOS, RSSI coupled with Bluetooth Low Energy (BLE) seems ideal in terms of market availability, cost-/energy-efficiency and scalability that affect competing technologies, provided it achieves adequate accuracy. Our work reports and discusses findings of a BLE/RSSI-based pilot, implemented at the Museum of Modern Greek Culture in Athens, involving eight buildings with 47 halls with diverse areas, shapes, and showcase layouts. Wearable visitor BLE beacons provided cell-level location determined by a prototype tool (VTT), integrating in its architecture different functionalities: raw RSSI data smoothing with Kalman filters, hybrid positioning provision, temporal methods for visitor cell prediction, spatial filtering, and prediction based on popular machine learning classifiers. Visitor movement modeling, based on critical parameters influencing signal measurements, provided scenarios mapped to popular behavioral models. One such model, {\textquotedblleft}ant{\textquotedblright}, corresponding to relatively slow nomadic cell roaming, was selected for basic experimentation. Pilot implementation decisions and methods adopted at all layers of the VTT architecture followed the overall concept of simplicity, availability, and cost-efficiency, providing a maximum infrastructure cost of 8 Euro per m2 covered. A total 15 methods/algorithms were evaluated against prediction accuracy across 20 RSSI datasets, incorporating diverse hall cell allocations and visitor movement patterns. RSSI data, temporal and spatial management with simple low-processing methods adopted, achieved a maximum prediction accuracy average of 81.53\% across all datasets, while ML algorithms (Random Forest) achieved a maximum prediction accuracy average of 87.24\%.

}, keywords = {Bluetooth Low Energy, indoor proximity positioning, large/complex museums, machine learning classification, museum visitor modeling, RSSI temporal/spatial methods}, issn = {1424-8220}, doi = {https://doi.org/10.3390/s25092713}, url = {https://doi.org/10.3390/s25092713}, author = {Philippopoulos, Panos I. and Koutrakis, Kostas N. and Tsafaras, Efstathios D. and Papadopoulou, Evangelia G. and Sigalas, Dimitrios and Tselikas, Nikolaos D. and Ougiaroglou, Stefanos and Costas Vassilakis} } @article {837, title = {Challenges and Trends in Student Evaluation of Teaching: Analysis of SET Data from the University of Peloponnese}, journal = {Information}, volume = {15}, year = {2024}, month = {09/2024}, pages = {576}, abstract = {

This study examines the effectiveness of Student Evaluations of Teaching at the University of Peloponnese, which has systematically collected anonymous evaluations since 2015. The analysis focused on participation rates, average scores, and the correlation between student evaluations and their academic performance. Participation rates were notably low, averaging 14.63\%, with postgraduate students showing higher rates (27.33\%) than undergraduates (10.77\%). The average SET scores were moderately high, with postgraduates rating their courses slightly better (M = 4.137) than undergraduates (M = 3.899). A weak positive correlation was found between course grades and evaluations among undergraduates, whereas no significant correlation was observed for postgraduates. These findings highlight challenges in using SETs as reliable measures of teaching effectiveness and suggest the need for improved participation and more comprehensive evaluation methods. The results provide insights into enhancing assessment practices and contribute to the broader discourse on the validity of student evaluations in higher education.

}, keywords = {Higher Education, quality assurance, SET}, issn = {2078-2489}, doi = {10.3390/info15090576}, author = {Papadogiannis, Ilias and Costas Vassilakis and Wallace, Manolis and Katsis, Athanassios} } @conference {838, title = {Estimating MPdist with SAX and Machine Learning}, booktitle = {New Trends in Database and Information Systems (Proceedings of ADBIS 2024, Short Papers, Workshops, Doctoral Consortium and Tutorials)}, year = {2024}, publisher = {Springer Cham}, organization = {Springer Cham}, abstract = {

MPdist is a distance measure which considers two time series to be similar if they share many similar subsequences. However, computing MPdist can be slow, especially for large time series. We propose a technique for the approximate computation of MPdist that uses the SAX representation of the time series to quickly estimate the Nearest Neighbor (NN) distance of each subsequence, and then applies a Machine Learning model to correct the accuracy loss incurred. Our method is orders of magnitude faster than the exact computation of MPdist; at the same time, our best approximation computes the NN of a time series with high accuracy. A thorough evaluation of our technique is provided.

}, keywords = {Distance metric, Machine Learning, MPdist, Random Forest, SAX, Time series}, doi = {https://doi.org/10.1007/978-3-031-70421-5_32}, author = {Mihalis Tsoukalos and Pantelis Chronis and Nikos Platis and Costas Vassilakis}, editor = {Joe Tekli and Johann Gamper and Richard Chbeir and Yannis Manolopoulos and Salma Sassi and Mirjana Ivanovic and Vargas-Solar, Genoveva and Ester Zumpano} } @article {835, title = {On the Quality and Validity of Course Evaluation Questionnaires Used in Tertiary Education in Greece}, journal = {Trends in Higher Education}, volume = {3}, year = {2024}, pages = {221{\textendash}234}, abstract = {

In compliance with national legislation, Greek tertiary education institutions assess educational quality often using a standardized anonymous questionnaire completed by students. This questionnaire aims to independently evaluate various course components, including content organization, instructor quality, facilities, infrastructure, and grading methods. Despite widespread use across universities, the questionnaire{\textquoteright}s validity remains unexamined. This study addresses this gap by analyzing 48,000+ questionnaire responses from the University of the Peloponnese (2014{\textendash}2022), encompassing 68 undergraduate and graduate programs. Confirmatory factor analyses were used to assess the quality of the questionnaire, while exploratory factor analyses were used to assess the dimensions of the tool based on the data. Both analyses reveal shortcomings: confirmatory analysis detects strong correlations between supposedly different factors, and exploratory analysis identifies dimensions inconsistent with the expected structure. These findings question the questionnaire{\textquoteright}s quality and the validity of drawn conclusions, while additionally identifying opportunities for reducing the number of questions, which can contribute to increased questionnaire submission rates. Given its common use across Greek universities and its influence on shaping courses, urgent redesigning of the questionnaire for tertiary education evaluation is recommended.

}, keywords = {CFA, EFA, Higher Education, quality assurance}, doi = {https://doi.org/10.3390/higheredu3020013}, url = {https://www.mdpi.com/2813-4346/3/2/13}, author = {Papadogiannis, Ilias and Costas Vassilakis and Wallace, Manolis and Katsis, Athanassios} } @article {827, title = {An Assessment of the Effectiveness of the Remedial Teaching Education Policy}, journal = {Knowledge}, volume = {3}, year = {2023}, month = {jul}, pages = {349{\textendash}363}, abstract = {

The remedial teaching policy is a flagship education policy of the Greek Ministry of Education that aims to create a school of equal opportunities by providing additional support to students from disadvantaged social backgrounds. In this work we utilised a data set provided by the Ministry of Education, followed a black box approach and built on previous results in order to achieve the first ever evaluation, based on data, of the remedial teaching policy. Our findings indicate that remedial teaching is very effective in supporting very weak students, helping 70\% of them achieve better academic performance and one out of three of them to sustain this enhanced academic performance in the future, long after they have stopped receiving remedial teaching. On the other hand, and contrary to what is widely believed, our results show that remedial teaching has the opposite impact to what it was designed for, as it is primarily the privileged students that receive the benefits. Consequently, in the way it is currently implemented, remedial teaching widens the gap between privileged and disadvantaged students rather than reduces it. The implications of the work are wide and far reaching, including the establishment of the need to revisit the way remedial teaching is implemented, the highlighting of the value in the data gathered by the Ministry of Education and the proof that individual educational policies can be objectively assessed despite being part of a complex system in which multiple education policies are implemented concurrently.

}, keywords = {black box evaluation, data driven evaluation, education policy, remedial teaching}, doi = {https://doi.org/10.3390/knowledge3030024}, url = {https://doi.org/10.3390/knowledge3030024}, author = {Ilias Papadogiannis and Manolis Wallace and Vassilis Poulopoulos and Costas Vassilakis and Georgios Lepouras and Nikos Platis} } @article {828, title = {Chatbots for Cultural Venues: A Topic-Based Approach}, journal = {Algorithms}, volume = {16}, year = {2023}, month = {jul}, pages = {339}, abstract = {

Digital assistants{\textemdash}such as chatbots{\textemdash}facilitate the interaction between persons and machines and are increasingly used in web pages of enterprises and organizations. This paper presents a methodology for the creation of chatbots that offer access to museum information. The paper introduces an information model that is offered through the chatbot, which subsequently maps the museum{\textquoteright}s modeled information to structures of DialogFlow, Google{\textquoteright}s chatbot engine. Means for automating the chatbot generation process are also presented. The evaluation of the methodology is illustrated through the application of a real case, wherein we developed a chatbot for the Archaeological Museum of Tripolis, Greece.

}, keywords = {chatbots, cultural venues, Museums, RDF triples, topics}, doi = {10.3390/a16070339}, url = {https://doi.org/10.3390/a16070339}, author = {Vasilis Bouras and Dimitris Spiliotopoulos and Dionisis Margaris and Costas Vassilakis and Konstantinos Kotis and Angeliki Antoniou and George Lepouras and Manolis Wallace and Vassilis Poulopoulos} } @conference {826, title = {EnQuest: A Cloud Datalake Infrastructure for Heterogeneous Analytics in Maritime and Tourism Domains}, booktitle = {DATA 2023 (demo)}, year = {2023}, abstract = {

Within recent years, transportation and supply chain have been affected by an avalanche of data including IoT devices, online services, social media and others. However, the implemented solutions so far are fragmented, physically distributed, require specialized IT knowledge to deploy, and involve significant IT experience to operate even for trivial tasks. In the context of the ENIRISST+ project, we developed EnQuest1, an online data lake that allows users without any IT background to harvest, store, organize, analyze and share heterogeneous, multi-faceted maritime/tourism data. EnQuest provides a zero-administration, zero-cost, integrated framework that enables scientists, practitioners and other stakeholders within the above domains to easily: (i) deploy data acquisition services (crawlers, dataset imports, questionnaire forms), (ii) design and manage versatile customizable data stores, (iii) share whole datasets or horizontal/vertical data shards with other stakeholders, (iv) search, filter and analyze data via an expressive yet simple-to-use graphical query engine and visualization tools, and (v) perform user management and access control operations on the stored data. To the best of our knowledge, this is the first approach in the literature that targets users without an IT background and focuses on collecting, managing, analyzing, and sharing diverse, multi-faceted data in maritime the and tourism sectors. The main goals of the proposed demonstration are to showcase the EnQuest system to the conference participants and promote the work of the ENIRISST+ project consortium. During the demo we will (i) deploy social media crawlers to gather maritime data and show the participants how to process and visualise them, (ii) create live questionnaires using the EnQuest functionality, ask the participants to fill them in and demonstrate the live processed data on appropriate dashboards, and (iii) demonstrate how to import data and subscribe to data flows of other users through the implemented publish/subscribe module. For the needs of the demo we will only require internet connection and a desk; we will have our own laptops to use at the demonstration.

}, keywords = {big data, cloud systems, data analytics, datalakes, maritime, tourism}, author = {Kimon Deligiannis and Christos Tryfonopoulos and Paraskevi Raftopoulou and Nikos Platis and Costas Vassilakis} } @conference {829, title = {Estimating \iSAX Parameters for Efficiency}, booktitle = {New Trends in Database and Information Systems (Proceedings of the 2023 European Conference on Advances in Databases and Information Systems / ADBIS 2023)}, year = {2023}, publisher = {Springer Nature Switzerland}, organization = {Springer Nature Switzerland}, address = {Cham}, abstract = {

\iSAX is considered one of the most efficient indexes for time series. Several parameters affect the construction of an \iSAX index: the sliding window size, the threshold value, the number of segments and the maximum cardinality, the last two being related to the SAX representation. In this paper (i) we consider the effect of each parameter on the efficiency of the \iSAX index, (ii) we evaluate the importance of each parameter, and, (iii) suggest how to optimize these parameters.

}, keywords = {Indexing, Parameter tuning, SAX, Time series}, isbn = {978-3-031-42941-5}, doi = {10.1007/978-3-031-42941-5_1}, author = {Tsoukalos, Michalis and Platis, Nikos and Costas Vassilakis} } @conference {825, title = {Estimating \iSAX Parameters for Efficiency}, booktitle = {Proceedings of the 27th European Conference on Advances in Databases and Information Systems (ADBIS 2023)}, year = {2023}, abstract = {

\iSAX is considered one of the most efficient indexes for time series. Several parameters affect the construction of an \iSAX index: the sliding window size, the threshold value, the number of segments and the maximum cardinality, the last two being related to the SAX representation. In this paper (i) we consider the effect of each parameter on the efficiency of the \iSAX index, (ii) we evaluate the importance of each parameter, and, (iii) suggest how to optimize these parameters.

}, keywords = {Indexing, Parameter tuning, SAX, Time series}, author = {Tsoukalos, Michalis and Platis, Nikos and Costas Vassilakis} } @conference {824, title = {Implementing the infrastructure for Dimitris Papaioannou{\textquoteright}s archive:approaching the degrees of separation in his work}, booktitle = {DARIAH 2023 (poster presentation)}, year = {2023}, abstract = {

Creating the infrastructure for an archive is considered, nowadays, to be a trivial procedure. Several tools (e.g. Omeka [2], CollectiveAccess[3], CollectionSpace[4]) and prototypes (eg. Dublin Core [5], VRA CORE [6]) are available for use in order to, either directly install and use a CMS for cultural related data (first case), or build a system {\textquotedblleft}from scratch{\textquotedblright} based on a common prototype (second case). This procedure would lead to the digitization of at least an archive{\textquoteright}s metadata and to the organization of the archive itself; it would offer the ability to search for information in the archive in an easy way, it would allow people to access the information of the archive, and it could also be part of a larger cultural data lake (Europeana). The solutions for these use cases, are extant, present and available. On the other hand, occasionally one comes across archives of artists that have a special view of art, are ahead of their time, design their own universe, and they keep evolving it throughout their life. In this paper, we discuss the implementation of the archive for Dimitiris Papaioannou, a diverse archive which includes several different types of data. In this case, we have selected a special approach, in order to fully capture the artistic aspects of the archive{\textquoteright}s content, which was analyzed in the context of the GENESIS project [1]. Throughout this project, the procedure through which the artist approaches the performance arts and generates ideas was recorded and analyzed. Following the aforementioned analysis, the archive material provides insight for the artist{\textquoteright}s visual arts, his dancing roads and his performances, and unveils his approach to performance arts (or art, in general). Then, the archive is structured in a way that would allow all archive visitors, including the general public as well as researchers, to obtain information about the individual elements of the work, but also locate the {\textquotedblleft}genetic material{\textquotedblright} of the artist into the archive. To achieve this goal, interdisciplinary research involving the cooperation of scientists and researchers from both the humanities and the technology domains was required. The research team designed an information layer entailing objective information (e.g. works, performances, participants and their roles etc.) and subjective information (e.g. tagging or free text descriptions), and accommodating semantic links between them. Metadata were also associated to information items, where applicable. The information layer fully serves the needs for information search and retrieval, while it additionally provides the underpinnings for data mining procedures that can possibly reveal patterns or data correlations that have remained unobserved.

}, keywords = {cultural informatics, Cultural Metadata, Cultural Semantics, Performance art}, author = {Vassilis Poulopoulos and Eleni Papalexiou and Costas Vassilakis and Avra Xepapadakou and Valia Vraka} } @conference {812, title = {Persona Finetuning for Online Gaming using Personalisation Techniques}, booktitle = {Proceedings of the 2022 HCII Conference}, year = {2022}, abstract = {

Automatic persona generation has been shown to have specific measurable benefits for application creators and users. In most situations, personas are adequately descriptive and diversified to achieve user type accuracy and coverage. For specific market segments, such as online gaming, using personas may accurately describe existing user base but not changing habit and need that are introduced by the fluidity of the offerings and the delivery methods. Changes in the ways that applications are marketed, such as new payment methods, for example, subscription models, pay-to-play and pay-to-win, payment-driven-gamification, seriously affect user needs and result in direct impact on user acceptance. This work utilises structured user needs from online gaming players to augment personas using personalisation techniques. The personas are finetuned and dediversified to result in concise personas, based on user needs that successfully convey information for creators and users alike.

}, keywords = {collaborative filtering, Data-driven methods, Diversification, Online Gaming, Persona, Personalisation, Usability evaluation, User study}, author = {Dimitris Spiliotopoulos and Dionisis Margaris and Kostas N. Koutrakis and Panos Philippopoulos and Costas Vassilakis} } @conference {809, title = {Digital applications for the preservation of historic memory: the case of the Kalamata digital museum (greek title: Ψηφιακές εφαρμογές για τη διατήρηση της ιστορικής μνήμης: Η περίπτωση του ψηφιακού μουσείου Καλαμάτας)}, booktitle = {4th PanHellenic Conference on Digital Cultural Heritage-EuroMed 2021}, year = {2021}, abstract = {

The evolution in technology and informatics have changed all aspects of our lives, including civilization-related ones. And while interdisciplinary research involving the scientific disciplines of human sciences and informatics was underdeveloped for many years, it seems that informatics and technology can constitute the catalyst for the rapid advancement of certain areas in human sciences. This has become more than apparent during the last decade, especially in museums and venues related to civilization, where the application of technology, both for the improvement of the visitors{\textquoteright} experience and for the support of scientists (archaeologists, museologists etc), is now taken as granted. In particular, the measures that have been applied during the last two years of the COVID19 pandemic, further accelerate the developments towards digitalization and switching to an online world. The "Kalamata 1821: roads of freedom" project was the starting point for the creation of the first mixed digital museum in the region of the Peloponnese; this museum is strongly related to the history of Greece, starting from the Revolution of 1821 and its relationship with Kalamata. This paper analyses the process of design, preparation and implementation of digital multimedia applications that are installed on the digital museum infrastructure. The applications have been designed to maximize the information that can be perceived within the limited time frame during of a museum visit, offering in parallel means to obtain some of the information presented and store them on a mobile device.

}, author = {Poulopoulos, Vassileios and Wallace, Manolis and Antoniou, Antzela and Costas Vassilakis and Panagiotidi, Vayia and Zacharias, Nikolaos} } @conference {801, title = {An Interface for User-Centred Process and Correlation Between Large Datasets}, booktitle = {Proceedings of the 2021 International Conference on Human-Computer Interaction: Design, User Experience, and Usability: UX Research and Design}, year = {2021}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {

Standard database query systems are designed to process data on a single installation only, and do not provide optimal solutions for cases that data from multiple sources need to be queried. In these cases, the sources may have different data schemata, data representations etc., necessitating extensive coding and data transformations to retrieve partial results and combine them to reach the desired outcome. Differences in schemata and representations may be subtle and remain unnoticed, leading to the production of erroneous results. The goal of this paper is to present an easy-to-use solution for the end users, enabling them to query data from a given set of databases through a single user interface. This user interface allows users to visualize database contents and query results, while facilities for uploading and validating the data are also accommodated. To demonstrate the applicability of our approach, a use case is presented where data from two different sources are uploaded into the system and thereafter the data from the two databases can be utilized in tandem. The usability evaluation involved software developers in free evaluation scenarios.

}, keywords = {big data, Multiple data sources, Query, Usability, user interface, Visualisation}, isbn = {978-3-030-78221-4}, doi = {https://doi.org/10.1007/978-3-030-78221-4_32}, author = {Spiliotopoulos, Dimitris and Giannakopoulos, Theodoros and Costas Vassilakis and Wallace, Manolis and Lantzouni, Marina and Poulopoulos, Vassilis and Dionisis Margaris} } @article {788, title = {Examining the use of STEAM Education in Preschool Education}, journal = {European Journal of Engineering Research and Science}, volume = {TBD}, year = {2020}, month = {TBD}, abstract = {

STEAM (Science, Technology, Engineering, Arts and Mathematics) initiatives are of current interest for both in-school and out-of-school contexts in North America. This is a new concept which is shifting educational paradigms towards art integration in STEM subjects. This article focuses on the need for STEAM education at the early childhood level and investigates the teaching and educational models of STEAM education in the kindergarten and in the first grades of primary school and how pre-school and primary school teachers see these models in the Greek context but also what students eventually learn from these models. The purpose of this chapter is to better understand the educational programs of STEAM education, which are offered by non-profit organizations and both public and private schools. Preschool children have a natural disposition toward science with their sense of curiosity and creativity. More research needs to be done in the area of STEAM implementation in the K-8 classrooms to incorporate engineering education.

}, keywords = {Early science education, Greek STEAM implementation, K-8 STEAM, STEAM educational models, STEM/STEAM education}, author = {C. Spyropoulou and M. Wallace and Costas Vassilakis and V. Poulopoulos} } @conference {lykourentzou_2019_crops, title = {Exploring Self-organisation in Crowd Teams}, booktitle = {Proceedings of the Crowd-Powered e-Services (CROPS) Workshop in the context of the 19th IFIP Conference on e-Business, e-Services and e-Society (I3E 2019)}, year = {2020}, month = {01/2020}, abstract = {

Online crowds have the potential to do more complex work in teams, rather than as individuals. Team formation algorithms typically maximize some notion of global utility of team output by allocating people to teams or tasks. However, decisions made by these algorithms do not consider the decisions or preferences of the people themselves. This paper explores a complementary strategy, which relies on the crowd itself to self-organize into eective teams. Our preliminary results show that users perceive the ability to choose their teammate extremely useful in a crowdsourcing setting. We also nd that self-organisation makes users feel more productive, creative and responsible for their work product.

}, keywords = {computer-supported collaboration, creative writing, crowd teams, self-organization}, doi = {10.1007/978-3-030-39634-3_15}, author = {Ioanna Lykourentzou and Antonios Liapis and Costas Papastathis and Konstantinos Papangelis and Costas Vassilakis} } @article {723, title = {A Fine-grained Social Network Recommender System}, journal = {Social Network Analysis and Mining}, volume = {10}, year = {2020}, abstract = {Recommender systems have greatly evolved in recent years and have become an integral part of the Web. From e-commerce sites to mobile apps, our daily routine revolves around a series of {\textquotedblleft}small{\textquotedblright} decisions that are influenced by such recommendations. In a similar manner, online social networks recommend only a subset of the massive amount of content published by a user{\textquoteright}s friends. However, the prevalent approach for the content selection process in such systems is driven by the amount of interaction between the user and the friend who published the content. As a result, content of interest is often lost due to weak social ties. In this paper, we present a fine-grained recommender system for social ecosystems, designed to recommend media content (e.g., music videos, online clips) published by the user{\textquoteright}s friends. The system design was driven by the findings of our qualitative user study that explored the value and requirements of a recommendation component within a social network. The core idea behind the proposed approach was to leverage the abundance of preexisting information in each user{\textquoteright}s account for creating interest profiles, to calculate similarity scores at a fine-grained level for each friend. The intuition behind the proposed method was to find consistent ways to obtain information representations that can identify overlapping interests in very specific sub-categories (e.g., two users{\textquoteright} music preferences may only coincide on hard rock). While the system is intended as a component of the social networking service, we developed a proof-of-concept implementation for Facebook and explored the effectiveness of our underlying mechanisms for content analysis. Our experimental evaluation demonstrates the effectiveness of our approach, as the recommended content of interest was both overlooked by the existing Facebook engine and not contained in the users{\textquoteright} Facebook News Feed. We also conducted a user study for exploring the usability aspects of the prototype and found that it offers functionality that could significantly improve user experience in popular services.}, keywords = {Content Analysis, Interest Profiles, Recommender Systems, Social Networks, Usability}, issn = {1869-5469}, doi = {10.1007/s13278-019-0621-7}, author = {Markos Aivazoglou and Antonios Roussos and Dionisis Margaris and Costas Vassilakis and Sotiris Ioannidis and Jason Polakis and Dimitris Spiliotopoulos} } @article {772, title = {Hydria: An Online Data Lake for Multi-Faceted Analytics in the Cultural Heritage Domain}, journal = {Big Data and Cognitive Computing}, volume = {4}, year = {2020}, pages = {7}, abstract = {Advancements in cultural informatics have significantly influenced the way we perceive, analyze, communicate and understand culture. New data sources, such as social media, digitized cultural content, and Internet of Things (IoT) devices, have allowed us to enrich and customize the cultural experience, but at the same time have created an avalanche of new data that needs to be stored and appropriately managed in order to be of value. Although data management plays a central role in driving forward the cultural heritage domain, the solutions applied so far are fragmented, physically distributed, require specialized IT knowledge to deploy, and entail significant IT experience to operate even for trivial tasks. In this work, we present Hydria, an online data lake that allows users without any IT background to harvest, store, organize, analyze and share heterogeneous, multi-faceted cultural heritage data. Hydria provides a zero-administration, zero-cost, integrated framework that enables researchers, museum curators and other stakeholders within the cultural heritage domain to easily (i) deploy data acquisition services (like social media scrapers, focused web crawlers, dataset imports, questionnaire forms), (ii) design and manage versatile customizable data stores, (iii) share whole datasets or horizontal/vertical data shards with other stakeholders, (iv) search, filter and analyze data via an expressive yet simple-to-use graphical query engine and visualization tools, and (v) perform user management and access control operations on the stored data. To the best of our knowledge, this is the first solution in the literature that focuses on collecting, managing, analyzing, and sharing diverse, multi-faceted data in the cultural heritage domain and targets users without an IT background.}, keywords = {analytics and visualization, big data management, Cultural heritage, data lake, data store, open source}, doi = {10.3390/bdcc4020007}, url = {https://www.mdpi.com/2504-2289/4/2/7}, author = {Kimon Deligiannis and Paraskevi Raftopoulou and Christos Tryfonopoulos and Nikos Platis and Costas Vassilakis} } @conference {784, title = {MOOC Accessibility from the Educator Perspective}, booktitle = {Proceedings of the 22nd International Conference on Human-Computer Interaction}, year = {2020}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

This work presents the universal access design principles and methods for natural language communication design in e-learning for the disabled. It unfolds a theoretical perspective to the design-for-all methodology and provides a framework description for technologies for creating accessible content for educational content communication. Main concerns include the problem identification of design issues for universal accessibility of spoken material, the primary pedagogical aspects that such content implementation should follow upon, as well as look into the state of the most popular e-learning platforms for which educators create and communicate educational content in an e-learning environment. References to massive open online course platform types of content that exist at the moment are examined in order to understand the challenges of bridging the gap between the modern design of rich courses and universal accessibility. The paper looks into the existing technologies for accessibility and a frame for analysis, including methodological and design issues, available resources and implementation using the existing technologies for accessibility and the perception of the designer as well as the user standpoint. Finally, a study to inform and access how potential educators may perceive the accessibility factor shows that accessible content is a major requirement toward a successful path to universally accessible e-learning.

}, keywords = {design-for-all, interactive e-learning, MOOC, speech processing, technologies for accessibility, universal accessibility}, url = {10.1007/978-3-030-60149-2_10}, author = {Dimitris Spiliotopoulos and Vassilis Poulopoulos and Dionisis Margaris and Eleni Makri and Costas Vassilakis} } @article {770, title = {A Semantic Mixed Reality Framework for Shared Cultural Experiences Ecosystems}, journal = {Big Data and Cognitive Computing}, volume = {4}, year = {2020}, month = {4/2020}, pages = {6}, abstract = {This paper presents SemMR, a semantic framework for modelling interactions between human and non-human entities and managing reusable and optimized cultural experiences, towards a shared cultural experience ecosystem that might seamlessly accommodate mixed reality experiences. The SemMR framework synthesizes and integrates interaction data into semantically rich reusable structures and facilitates the interaction between different types of entities in a symbiotic way, within a large, virtual, and fully experiential open world, promoting experience sharing at the user level, as well as data/application interoperability and low-effort implementation at the software engineering level. The proposed semantic framework introduces methods for low-effort implementation and the deployment of open and reusable cultural content, applications, and tools, around the concept of cultural experience as a semantic trajectory or simply, experience as a trajectory (eX-trajectory). The methods facilitate the collection and analysis of data regarding the behaviour of users and their interaction with other users and the environment, towards optimizing eX-trajectories via reconfiguration. The SemMR framework supports the synthesis, enhancement, and recommendation of highly complex reconfigurable eX-trajectories, while using semantically integrated disparate and heterogeneous related data. Overall, this work aims to semantically manage interactions and experiences through the eX-trajectory concept, towards delivering enriched cultural experiences.}, keywords = {cultural experience, intelligent interaction, Mixed Reality, semantics, Usability}, doi = {https://doi.org/10.3390/bdcc4020006}, author = {Costas Vassilakis and Konstantinos Kotis and Dimitris Spiliotopoulos and Dionisis Margaris and Vlasios Kasapakis and Christos-Nikolaos Anagnostopoulos and Georgios Santipantakis and George A. Vouros and Theodore Kotsilieris and Volha Petukhova and Andrei Malchanau and Ioanna Lykourentzou and Kaj Michael Helin and Artem Revenko and Nenad Gligoric and Boris Pokric} } @article {787, title = {Visualizing the educational data mining literature}, journal = {European Journal of Engineering Research and Science}, volume = {TBD}, year = {2020}, month = {TBD}, abstract = {

This article provides a visualization of a literature review in students{\textquoteright} performance prediction using educational data mining (EDM) techniques for the period 2015-2019. The results of the review are presented concisely and simply with the use of diagrams. Various aspects of the literature are examined, such as the algorithms adopted, the type of results drawn, the educational setting of the application and the actual exploitation of the outcomes. Findings indicate that tertiary education dominates the EDM field; in contrast, the focus given to secondary and primary education is minimal.

}, keywords = {Educational Data Mining, Literature review, Student Performance, Visualization}, author = {I. Papadogiannis and N. Platis and V. Poulopoulos and Costas Vassilakis and G. Lepouras and M. Wallace and G. Karountzou} } @conference {Antoniou_2019_Mytilene, title = {Cultural technologies: the case of the Tripolis archeological museum (in Greek; Greek title: "ΠΟΛΙΤΙΣΤΙΚΕΣ ΤΕΧΝΟΛΟΓΙΕΣ: Η ΠΕΡΙΠΤΩΣΗ ΤΟΥ ΑΡΧΑΙΟΛΟΓΙΚΟΥ ΜΟΥΣΕΙΟΥ ΤΡΙΠΟΛΗΣ")}, booktitle = {Book of abstracts of the 2nd Conference of the School of Social Sciences of the University of the Aegean "Social sciences today: dilemmas and prospectives beyond the crisis"}, year = {2019}, abstract = {The Tripolis archeological museum hosts magnificent ancient art exhibits from the whole of the Arcadia county. However, a series of issues, including the old-style museological exhibition and the limited informational material offered to the visitor, combined with the lack of digital presence for the museum, lead to a low number of visitors. Culural technologies may offer solutions to these issues that the museum fronts, and to this end the museum was included in the CrossCult EU project (www.crosscult.eu). In the context of the project, the antecendents regarding the technological design for the particular museum were studied (staff, visitor and technological equipment needs), and the characteristics of the museum collections were examined. With the collaboration of the Ephorate of Antiquities of Arcadia, the most important and characteristic exhibits were identified, among those that were linked to the position of the woman in the ancient society. Using these exhibits as a basis, 7 thematic itineraries were created in both the English and the Greek language, which support the user in visiting the museum halls and exhibitions and learning certain aspects of women{\textquoteright}s lives in the antiquity (e.g. education, everyday life, social status, etc). Each exhibit is linked with different digital cultural artefacts (e.g. images from other collections, related videos, games, sound clips etc.), to create narratives that increase user engagement and stimulate reflection. In parallel, a series of games was deveped, aiming to disseminate the presence of the museum and the information sourced from it through the social networks, assist in creating user profiles and further promote the museum. Finally, user experience can continue after the visit, through the use of a specialized social network, created specifically for the needs of the museum. (Abstract in Greek follows: Το αρχαιολογικό μουσείο Τρίπολης στεγάζει καταπληκτικά δείγματα αρχαίας τέχνης από ολόκληρο τον νομό Αρκαδίας. Όμως μια σειρά προβλημάτων, όπως η παλαιού τύπου μουσειολογική έκθεση και το πολύ συνοπτικό πληροφοριακό υλικό που προσφέρεται στον επισκέπτη, μαζί με το γεγονός ότι το μουσείο δεν έχει ψηφιακή παρουσία, οδηγεί σε χαμηλή επισκεψιμότητα. Οι πολιτιστικές τεχνολογίες μπορούν να προσφέρουν λύσεις στα προβλήματα του μουσείου και έτσι το μουσείο εντάχθηκε στο Ευρωπαϊκό ερευνητικό έργο CrossCult (www.crosscult.eu). Μέσα στα πλαίσια του έργου, μελετήθηκαν τα προαπαιτούμενα σχεδιασμού τεχνολογιών για το συγκεκριμένο χώρο (ανάγκες προσωπικού, ανάγκες επισκεπτών, ανάγκες τεχνολογικού εξοπλισμού), καθώς και τα χαρακτηριστικά των συλλογών. Με τη βοήθεια της Εφορείας Αρχαιοτήτων Αρκαδίας, εντοπίστηκαν τα σημαντικότερα και χαρακτηριστικότερα εκθέματα, γύρω από το θέμα της θέσης της γυναίκας στον αρχαίο κόσμο. Με βάσει τα εκθέματα αυτά, δημιουργήθηκαν 7 θεματικές διαδρομές (σε Ελληνικά και Αγγλικά) όπου ο επισκέπτης μπορεί να περιηγηθεί στο μουσείο και να μάθει για συγκεκριμένες πτυχές της ζωής των γυναικών (π.χ. εκπαίδευση, καθημερινότητα, κοινωνική θέση, κλπ). Το κάθε έκθεμα συνδέεται με διαφορετικά ψηφιακά πολιτιστικά αντικείμενα (π.χ. εικόνες από εκθέματα άλλων συλλογών, σχετικά βίντεο, παιχνίδια, αρχεία ήχου, κλπ) για να δημιουργηθούν αφηγήσεις που να αυξάνουν τον προβληματισμό και την εμπλοκή του επισκέπτη. Παράλληλα, μια σειρά παιχνιδιών υλοποιήθηκε με σκοπό τη διάχυση στα μέσα κοινωνικής δικτύωσης για τη δημιουργία προφίλ επισκεπτών και την περαιτέρω διαφήμιση του μουσείου. Τέλος, η εμπειρία μπορεί να συνεχιστεί και μετά την επίσκεψη με τη χρήση εξειδικευμένου κοινωνικού δικτύου, φτιαγμένου ειδικά για τους επισκέπτες του μουσείου.)}, url = {https://www.propobos.gr/?id=3247\&\&atfc=3250}, author = {Angela Antoniou and Giorgos Lepouras and Costas Vassilakis and Manolis Wallace and Nikos Platis} } @conference {725, title = {Kalamata 1821: Roads of Freedom - Digital applications teach history (Greek title: Καλαμάτα 1821: Δρόμοι Ελευθερίας {\textendash} Οι ψηφιακές εφαρμογές διδάσκουν ιστορία)}, booktitle = {2nd Panhellenic conference on Open Educational Resources and e-learning}, year = {2019}, abstract = {The {\textquotedblleft}Kalamata 1821: Roads of Freedom{\textquotedblright} project is an effort for scientifically organizing the celebration of the 200-year anniversary from the liberation of Greece from the Turkish thrall, with a special focus on the city of Kalamata. The project, aiming to link historical memories to the modern era, includes a major section related to the development of digital applications. The project{\textquoteright}s digital applications are developed by the Knowledge and Uncertainty lab of the Department of Informatics and Telecommunications of the University of the Peloponnese. The digital applications are based on the information provided by the historical scientific team of the project. Within the project, two distinct groups of applications are developed, in order to cover the diverse needs of the target population. The nature of the applications is clearly didactic, offering detailed information regarding historical facts, places and persons which relate to the Greek War of Independence, as well as on locations where important events took place. The Interactive Table applications are a group of applications which will be available to the public visiting the historic building of the old Town Hall of Kalamata, where the project exhibition center is located. These applications constitute a modern, interactive, digital encyclopedia of the relation between the city of Kalamata and the Greek War of Independence. For the Interactive Table, three original applications were developed. The first depicts histories and facts linked to some points on a map. The second presents a tree of histories, that is histories that are interrelated, and where each visitor may familiarize with facts and persons that are linked to each other. Finally, the third application focuses on images and multimedia, challenging the visitors to identify and elaborate on events and histories hiding behind pictures. The second group consists of a single application that targets on a wider public that prefers a different type on interaction. Effectively this application implements a scavenger hunt with historic content. The goal of this application is to motivate the visitor of the city of Kalamata to wander around the city, and also to link the project to the local market.}, keywords = {Educational applications, Interactive table, Mobile applications}, author = {M. Wallace and V. Poulopoulos and A. Antoniou and Costas Vassilakis and G. Lepouras and J. Diakoumakos and V. Panagiotidou} } @conference {718, title = {A Mixed-reality Interaction-driven Game-based Learning Framework}, booktitle = {Proceedings of the 11th International Conference on Management of Digital EcoSystems (MEDES{\textquoteright}19)}, year = {2019}, publisher = {ACM}, organization = {ACM}, abstract = {This work presents a platform for linked legislative data to engage citizens in transparent and effective democracies. With a focus on scaling up participatory approaches from local to national level, the approach extends well established and open source tools and technologies, to build mobile monitoring and analysis tools that increase transparency of law-making and implementation to citizens. This is achieved by combining open data and open services with user and citizen generated content, in order to address citizen{\textquoteright}s needs in the context of open government. Data and feeds from trusted sources are interconnected with new and re-purposed data feeds generated by users via the social web to form a meaningful, searchable, customizable, re-usable and open data-focused personalised mobile public service approach. The framework exploits the social aspects of open data, as well as the training of users, citizens and public servants to be able to understand and demand useful public open data, as well as facilitate the opening of more data.}, keywords = {Accountability, Citizen Engagement, e-government, Legislation, Mobile Public Services, Natural language processing, Policy Modelling, Transparency}, author = {Dimitris Spiliotopoulos and Dionisis Margaris and Costas Vassilakis and Volha Petukhova and Konstantinos Kotis} } @conference {714, title = {PaloAnalytics project concept, scope and outcomes: an opportunity for culture}, booktitle = {Proceedings of the Workshop on Cultural Informatics, co-located with the 14th International Workshop On Semantic And Social Media Adaptation And Personalization (SMAP 2019)}, year = {2019}, abstract = {This paper describes the national funded project entitled PaloAnalytics, which develops an innovative platform that allows companies and organizations, that operate in several countries, to monitor and analyze, in depth, the markets{\textquoteright} interest to their products and successfully plan their marketing and communication strategy, with data and insights collected from all the local media, and focuses on its application to cultural spaces and museums. In this notion, we examine the effect that this project can have in cultural spaces or companies related to arts and culture. PaloAnalytics platform allows organizations to investigate the impact of their products on consumers across different countries and this is achieved with the analysis of content from sites, blogs, social networks and open data. This implies that cultural organization can benefit by adopting the implemented services, so that the can recognize and analyze their audience, their online marketing campaigns as well as examine the impact of their messages and the spread of their messages on the Internet. In this paper, we briefly describe the project and discuss on the impact on cultural related organizations.}, keywords = {big data, data monitoring, Data visualization, deep learning, influencers, infographics, trending topics}, url = {http://ceur-ws.org/Vol-2412/paper7.pdf}, author = {Vassilis Poulopoulos and Manolis Wallace and Costas Vassilakis and George Lepouras}, editor = {Angeliki Antoniou and Manolis Wallace} } @conference {726, title = {Scavenger Hunt in the Roads of Freedom (Greek title: {\textquotedblleft}Κυνήγι θησαυρού στους Δρόμους της Ελευθερίας")}, booktitle = {Proceedings of the 3nd Pan-Hellenic Conference on Digital Cultural Heritage-EuroMed 2019}, year = {2019}, abstract = {The project "Kalamata 1821: Roads of freedom" is being funded in the context of the Action "RESEARCH - CREATE - INNOVATE. The project, which encompasses original historic research work in the University of the Peloponnese, is an effort to narrate a historic course of 200 years for the city of Kalamata, from the eruption of the Greek revolution until today, through a modern and fresh perspective. This paper will present one of the digital applications developed within the project, and more specifically the Scavenger Hunt that is being developed by the Knowledge and Uncertainty lab of the Department of Informatics and Telecommunications in Tripolis. The game is designed for mobile devices and its goal is to link the historic content of the project with the contemporary city and, in a gamified fashion, assist the user not only to familiarize with the history of the city but also to navigate in the city and connect with the local market. By searching through pictures of various locations of the city, the visitor is directed to the most outstanding locations of the war of independence, and learns about the contribution of the city of Kalamata in this turning point for the history of the Greek nation. At the same time, the visitor is rewarded by receiving offers for local stores.}, keywords = {Greek War of Independence, Kalamata, Roads of Freedom, Scavenger Hunt}, author = {Manolis Wallace and Vassilis Poulopoulos and George Lepouras and Costas Vassilakis and Angeliki Antoniou} } @conference {727, title = {Supporting small museums through social network semantic analysis (Greek title: Υποστήριξη μικρών μουσείων μέσω της σημασιολογικής ανάλυσης κοινωνικών δικτύων)}, booktitle = {Proceedings of the 3nd Pan-Hellenic Conference on Digital Cultural Heritage-EuroMed 2019}, year = {2019}, abstract = {Greece has a significant historic, archaeological and cultural wealth, and a big number of museums and related venues. Some of them are big, both in size and resources -human as well as financial. Most venues however are small in size, are not connected with larger organizations, have constrained budgets and little or no permanent staff. In this paper, we focus on that particular category of museums. Many of these museums possess noteworthy collections, and it would be desirable if the general public could enjoy them. Unfortunately, in most cases, even the existence of the museums is not generally known, even to inhabitants of the cities at which the museums are located. The small number of visitors leads to confined revenues, and this in turn leads to a situation which is not financially viable. In order for a small museum to survive, its existence and value must be made known to the wide public. However, this is inhibited due to the lack of resources to finance advertising and the lack of specialized personnel. In this paper, we combine our experiences on small museums, which has been developed within the CrossCult H2020 project, with know-how on social network analysis which has been gained in the context of the PaloAnalytics national project, in order to offer viable solutions for promotion, which are tailored to the needs of small museums.}, keywords = {semantic analysis, small-sized museums, Social Networks}, author = {Manolis Wallace and Vassilis Poulopoulos and George Lepouras and Costas Vassilakis and Angeliki Antoniou} } @conference {724, title = {TripMentor: Challenges and prospects for culture and tourism in the Attica region (Greek title: {\textquotedblleft}TripMentor: προκλήσεις και προοπτικές για τον πολιτισμό και τον τουρισμό στην περιφέρεια Αττικής{\textquotedblleft})}, booktitle = {Proceedings of the 3nd Pan-Hellenic Conference on Digital Cultural Heritage-EuroMed 2019}, year = {2019}, abstract = {This paper presents the TripMentor project which is related to the tourism and civilization in the region of Attica. The main goal of the project is the presentation, in two languages, of the rich cultural content of the region to the tourists, through an Internet-based environment and through mobile applications. The goal of the project is to guide the visitors through many possible alternative routes, which include points of interest, as well as enterprises with tourism-related offers, while at the same time attempts to combine these routes with cultural points of interest. The project interrelates information, venues and visitor profiles with an automated way, striving to offer a unique personalized experience, tailored to the needs and preferences of each user. The project challenges are mainly technical, since through the project procedures (a) information regarding the points of interest should be gathered in an automated fashion (b) information about events related to points of interest must be taken into account and (v) data related to users, and especially the user profiles must be discovered and exploited so that the available information can be synthesized into a unique experience. In this context, we present the project application domain and the related challenges.}, keywords = {cultural information, culture, geospatial data, Social Networks, tourism, visitor profile}, author = {Costas Vassilakis and Vassilis Poulopoulos and Manolis Wallace and Angeliki Antoniou and George Lepouras} } @conference {713, title = {TripMentor Project: scope and challenges}, booktitle = {Proceedings of the Workshop on Cultural Informatics, co-located with the 14th International Workshop On Semantic And Social Media Adaptation And Personalization (SMAP 2019)}, year = {2019}, abstract = {We present Tripmentor, a novel project, that is related to tourism in the region of Attica. The project has as main scope to provide rich media content to tourists through a web and mobile environment in two languages trying to guide them through alternative routes that include places of interest as well as organizations with offers to tourists. The project interconnects people with places and events in an automated manner trying to personalize on each tourist{\textquoteright}s personality. The challenges of the project are mainly technological as through the processes of the project a) automated information about venues must be collected, b) information about events related to venues must be fetched and finally c) data related to system users and mainly their profile should be discovered and created in order to offer a unique experience to each of them. We present the scope of the project as well as the challenges of its implementation.}, keywords = {cultural related information, geodata, personalization, social media, tourism, tripmentor}, url = {http://ceur-ws.org/Vol-2412/paper6.pdf}, author = {Costas Vassilakis and Vassilis Poulopoulos and Manolis Wallace and Angeliki Antoniou and George Lepouras}, editor = {Angeliki Antoniou and Manolis Wallace} } @article {DBLP:journals/bdr/Chatzigeorgakidis19, title = {Visual Exploration of Geolocated Time Series with Hybrid Indexing}, journal = {Big Data Research}, volume = {15}, year = {2019}, pages = {12{\textendash}28}, doi = {10.1016/j.bdr.2019.02.001}, url = {https://doi.org/10.1016/j.bdr.2019.02.001}, author = {Georgios Chatzigeorgakidis and Kostas Patroumpas and Dimitrios Skoutas and Spiros Athanasiou and Spiros Skiadopoulos} } @proceedings {DBLP:conf/pakdd/2018-2, title = {Advances in Knowledge Discovery and Data Mining - 22nd Pacific-Asia Conference, PAKDD 2018, Melbourne, VIC, Australia, June 3-6, 2018, Proceedings, Part II}, volume = {10938}, year = {2018}, publisher = {Springer}, isbn = {978-3-319-93036-7}, doi = {10.1007/978-3-319-93037-4}, url = {https://doi.org/10.1007/978-3-319-93037-4}, editor = {Dinh Q. Phung and Vincent S. Tseng and Geoffrey I. Webb and Bao Ho and Mohadeseh Ganji and Lida Rashidi} } @inbook {Vasilakis2018BigData, title = {Big Data Platforms and Applications}, year = {2018}, publisher = {Springer}, organization = {Springer}, chapter = {exhiSTORY: Smart self-organizing exhibits}, abstract = {Creating stories for exhibitions is a fascinating and in parallel laborious task. As every exhibition is designed to tell a story, museum curators are responsible for identifying, for each exhibit, its aspects that fit to the message of the story and position the exhibit at the right place in the story thread. In this context we analyze how the technological advances in the fields of sensors and Internet of Things can be utilized in order to construct a "smart space", which consists of self-organizing exhibits that cooperate with each other and provide visitors with comprehensible, rich, diverse, personalized and highly stimulating experiences. We present the system named "exhiSTORY" that intends to provide the appropriate infrastructure to be used in museums and places where exhibitions are held in order to support smart exhibits. The architecture of the system and its application potential is presented and discussed.}, author = {Costas Vassilakis and Vassilis Poulopoulos and Angela Antoniou and Manolis Wallace and Giorgos Lepouras and Martin Lopez Nores}, editor = {TBC} } @conference {poulopoulos2018a, title = {The Effect of Social Media Trending Topics Related to Cultural Venues{\textquoteright} Content}, booktitle = {2018 13th International Workshop on Semantic and Social Media Adaptation and Personalization (SMAP)}, year = {2018}, month = {sep}, publisher = {IEEE}, organization = {IEEE}, abstract = {Social media have gained the majority of attention on the Internet having an extreme number of daily visitors worldwide. The amount of information exchanged is vast, while users have become equally producers and consumers of data. Words like {\textquotedblleft}trending{\textquotedblright}, {\textquotedblleft}influencers{\textquotedblright}, {\textquotedblleft}likes{\textquotedblright} and {\textquotedblleft}viral{\textquotedblright} are in the daily agenda of data analyzers, as they are associated with factors that play an important role in the influence of social media content to its audience. These aspects are nowadays strongly taken into account by organizations that want to draw the public{\textquoteright}s attention to the content they deliver, and in this context cultural institutions have already started to take under great consideration not only their presence in social media, but also the exploitation of social media dynamics. In this paper we propose a method that can enable cultural venues to benefit from matches between their own content and ongoing discussions on social media. More specifically we extract trending topics that can be related semantically with the content of a cultural institute and examine how a venue can benefit by exploiting these matches. The proposed algorithm has been developed in the scope of the {\textquotedblleft}CrossCult{\textquotedblright} H2020 project, and has been experimentally tested by analyzing the case of Twitter in Greek language.}, keywords = {cultural informatics, cultural venues, personalization, social media, trending topics}, doi = {10.1109/SMAP.2018.8501878}, author = {Vassilis Poulopoulos and Costas Vassilakis and Manolis Wallace and Angela Antoniou and Giorgos Lepouras} } @conference {PoulopoulosGIIS2018, title = {ExhiSTORY: IoT in the service of Cultural Heritage}, booktitle = {Proceedings of the Global Information Infrastructure and Networking Symposium (GIIS 2018), Special Session on IoT and Cultural Heritage Protection}, year = {2018}, month = {oct}, publisher = {IEEE}, organization = {IEEE}, abstract = {Creating stories for exhibitions is a fascinating and in parallel laborious task. As every exhibition is designed to tell a story, museum curators are responsible for analyzing each exhibit in order to extract messages that form a story and position accordingly the objects in correct order within the museum space. In this context, we analyze how the technological advances in the fields of sensors and the Internet of Things can be utilized in order to construct a {\textquotedblleft}smart space{\textquotedblright}, where exhibits can communicate with the visitors and to each other and can be organized automatically so that they can generate rich, personalized, coherent and highly stimulating experiences. We present the architecture of the system named {\textquotedblleft}exhiSTORY{\textquotedblright}, that intends to provide the appropriate infrastructure to be used in museums and places where exhibitions are held, in order to support smart exhibits. We discuss and analyze the architecture of the system and the ways of its application in a cultural space.}, doi = {10.1109/GIIS.2018.8635759}, author = {Vassilis Poulopoulos and Costas Vassilakis and Angela Antoniou and Manolis Wallace and Giorgos Lepouras and Martin Lopez Nores} } @article {Vassilakis_fgcs17, title = {exhiSTORY: Smart Exhibits That Tell Their Own Stories}, journal = {Future Generation of Computer Systems}, volume = {81}, year = {2018}, pages = {542-556}, abstract = {Museum exhibitions are designed to tell a story; this story is woven by curators and in its context a particular aspect of each exhibit, fitting to the message that the story is intended to convey, is highlighted. Adding new exhibits to the story requires curators to identify for each exhibit its aspects that fit to the message of the story and position the exhibit at the right place in the story thread. The availability of rich semantic information for exhibits, allows for exploiting the wealth of meanings that museum exhibits express, enabling the automated or semi-automated generation of practically countless stories that can be told. Personalization algorithms can then be employed to choose from these stories the ones most suitable for each individual user, based on the semantics of the stories and information within the user profile. In this work we examine how opportunities arising from technological advances in the fields of IoT and semantics can be used to develop smart, self-organizing exhibits that cooperate with each other and provide visitors with comprehensible, rich, diverse, personalized and highly stimulating experiences. These notions are included in the design of a system named exhiSTORY, which also exploits previously ignored information and identifies previously unseen semantic links. We present the architecture of the system and discuss its application potential.}, keywords = {Cultural heritage, IoT, personalization, Quality of Experience (QoE), Self-organizing exhibitions, semantics}, doi = {https://doi.org/10.1016/j.future.2017.10.038}, url = {https://www.sciencedirect.com/science/article/pii/S0167739X17324093}, author = {Costas Vassilakis and Vassilis Poulopoulos and Angela Antoniou and Manolis Wallace and Giorgos Lepouras and Martin Lopez Nores} } @conference {DBLP:conf/edbt/Chatzigeorgakidis18, title = {Map-Based Visual Exploration of Geolocated Time Series}, booktitle = {Proceedings of the Workshops of the EDBT/ICDT 2018 Joint Conference (EDBT/ICDT 2018), Vienna, Austria, March 26, 2018.}, year = {2018}, pages = {92{\textendash}99}, url = {http://ceur-ws.org/Vol-2083/paper-14.pdf}, author = {Georgios Chatzigeorgakidis and Dimitrios Skoutas and Kostas Patroumpas and Spiros Athanasiou and Spiros Skiadopoulos} } @conference {vacilosEuromed18, title = {Personality Analysis of Social Media Influencers as a Tool for Cultural Institutions}, booktitle = {Digital Heritage. Progress in Cultural Heritage: Documentation, Preservation, and Protection}, year = {2018}, pages = {236{\textendash}247}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {Nowadays, more and more cultural venues tend to utilize social media as a main tool for marketing, spreading their messages, engaging public and raising public awareness towards culture. It comes to a point where the massive of content in social media makes it a tedious procedure to contact the appropriate audience, the people that would really be stimulated by cultural information. In this notion, we assume that establishing conversations of high impact can possibly guide the cultural venues to audiences that can benefit more. These conversations usually include the so called influencers, users whose opinion can affect many people on social media; the latter usually referred to as followers. In this research paper we examine the characteristics of the influencers that can affect the procedures of a cultural venue on social media. The research is done within the scope of "CrossCult" EU funded project.}, keywords = {cultural informatics, influencers, personality traits, social media, user modeling}, doi = {10.1007/978-3-030-01762-0_20}, author = {Vassilis Poulopoulos and Costas Vassilakis and Angela Antoniou and Giorgos Lepouras and Manolis Wallace} } @article {Poulopoulos2018Heritage, title = {The personality of the influencers, the characteristics of qualitative discussions and their analysis for recommendations to cultural institutions}, journal = {Heritage}, volume = {1}, number = {2}, year = {2018}, month = {oct}, pages = {239-253}, abstract = {Social media usage is affecting peoples{\textquoteright} views through opinion sharing, a fact that has started to attract cultural institutions, as it is possible that this procedure can possibly be a part of a museum experience. As the main goal of a cultural institution is the maximization of senses stimulation, the device that is offered to the visitors{\textquoteright} hands everyday and every moment, becomes an important tool for the art spaces. In this notion we perform research on issues that can be of great importance for the museum{\textquoteright}s online presence and attraction. We focus on establishing the personality of influencers related to culture, as well as the characteristics of qualitative discussions on the social media. Crosscult Project is an EU funded project, that aims to spur a change in the way European citizens appraise History, and sets that basis of our research as the experiments are conducted within its scope of. Through the experimental procedure, we collect information in order to define the character of the influencer and the substances of a {\textquotedblleft}serious{\textquotedblright} conversation. {\textquotedblleft}Serious{\textquotedblright} conversations are regarded the ones in which a cultural organization can participate actively and benefit from the participation. We present the results of our experimental evaluation and analyze how cultural institutions can benefit from the outcomes of our research.}, keywords = {cultural informatics, digital humanities, personality traits, personalization, serious conversations, social media influencers, user modeling}, issn = {2571-9408}, doi = {10.3390/heritage1020016}, url = {https://doi.org/10.3390/heritage1020016}, author = {Vassilis Poulopoulos and Costas Vassilakis and Angela Antoniou and Giorgos Lepouras and Anastasios Theodoropoulos and Manolis Wallace} } @conference {DBLP:conf/gis/Chatzigeorgakidis18, title = {Scalable hybrid similarity join over geolocated time series}, booktitle = {Proceedings of the 26th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems, SIGSPATIAL 2018, Seattle, WA, USA, November 06-09, 2018}, year = {2018}, pages = {119{\textendash}128}, doi = {10.1145/3274895.3274949}, url = {https://doi.org/10.1145/3274895.3274949}, author = {Georgios Chatzigeorgakidis and Kostas Patroumpas and Dimitrios Skoutas and Spiros Athanasiou and Spiros Skiadopoulos} } @article {DBLP:journals/jbi/PoulisLSG17, title = {Anonymizing datasets with demographics and diagnosis codes in the presence of utility constraints}, journal = {Journal of Biomedical Informatics}, volume = {65}, year = {2017}, pages = {76{\textendash}96}, doi = {10.1016/j.jbi.2016.11.001}, url = {https://doi.org/10.1016/j.jbi.2016.11.001}, author = {Giorgos Poulis and Grigorios Loukides and Spiros Skiadopoulos and Aris Gkoulalas-Divanis} } @article {DBLP:journals/bmcbi/ZagganasVPVSD17, title = {BUFET: boosting the unbiased miRNA functional enrichment analysis using bitsets}, journal = {BMC Bioinformatics}, volume = {18}, number = {1}, year = {2017}, pages = {399:1{\textendash}399:8}, doi = {10.1186/s12859-017-1812-8}, url = {https://doi.org/10.1186/s12859-017-1812-8}, author = {Konstantinos Zagganas and Thanasis Vergoulis and Maria D. Paraskevopoulou and Ioannis S. Vlachos and Spiros Skiadopoulos and Theodore Dalamagas} } @conference {antoniouEuromed2017, title = {Experiences from the development of thematic itineraries in three Greek museums (Greek title: Εμπειρίες από την ανάπτυξη θεματικών διαδρομών σε τρία Ελληνικά μουσεία)}, booktitle = {Proceedings of the 2nd PanHellenic conference on Cultural Heritage (Euromed 2017)}, year = {2017}, month = {12}, abstract = {Private museums, as well as a considerable number of public regional museums, are confined by the small exhibition space and the relatively small number of exhibits and therefore cannot develop multiple exhibitions to satisfy visitors with different interests and characteristics. In this paper we report on our experieces from developing multiple thematic itineraries in the Tegea Folklore Museum , in the Cretan open-air museum "Lychnostatis" in Heraclion, and in the Panarcadic Archaeological Museum of Tripolis. The thematic itineraries in the Tegea Folklore Museum are (a) space (b) technology and (c) clothing. In the Cretan open-air museum "Lychnostatis", the itineraries are (a) natural sciences,(b) popular art, (c) pre-industrial technology and (d) folklore. In the Panarcadic Archaeological Museum of Tripolis we have the following itineraries: (a) appearance/clothing, (b) mortality, (c) nudity, (d) religion, (e) social status, (f) education, (g) healing practices and (h) everyday life. Each itinerary exploits a subset of the available exhibits to present a selected subject and is adapted to the needs of a predetermined and focused group of the general public. The results from the application of the approach, insofar, have shown that this is a promising path, both regarding the better exploitation of the space and the exhibits of the small museums, as well as regarding the better adaptation to the interests of the visitors.}, author = {Angela Antoniou and Costas Vassilakis and Manolis Wallace and Giorgos Lepouras and Vassilis Poulopoulos} } @conference {DBLP:conf/gis/Chatzigeorgakidis17, title = {Indexing Geolocated Time Series Data}, booktitle = {Proceedings of the 25th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems, GIS 2017, Redondo Beach, CA, USA, November 7-10, 2017}, year = {2017}, pages = {19:1{\textendash}19:10}, doi = {10.1145/3139958.3140003}, url = {https://doi.org/10.1145/3139958.3140003}, author = {Georgios Chatzigeorgakidis and Dimitrios Skoutas and Kostas Patroumpas and Spiros Athanasiou and Spiros Skiadopoulos} } @article {DBLP:journals/tkde/TerrovitisPMS17, title = {Local Suppression and Splitting Techniques for Privacy Preserving Publication of Trajectories}, journal = {IEEE Trans. Knowl. Data Eng.}, volume = {29}, number = {7}, year = {2017}, pages = {1466{\textendash}1479}, doi = {10.1109/TKDE.2017.2675420}, url = {https://doi.org/10.1109/TKDE.2017.2675420}, author = {Manolis Terrovitis and Giorgos Poulis and Nikos Mamoulis and Spiros Skiadopoulos} } @conference {theodorakopoulos-smap2017, title = {Personalized Augmented Reality Experiences in Museums using Google Cardboards}, booktitle = {2017 12th International Workshop on Semantic and Social Media Adaptation and Personalization (SMAP)}, year = {2017}, month = {07}, publisher = {IEEE CPS}, organization = {IEEE CPS}, abstract = {In this short paper we examine the suitability of the Google Cardboard as a means for the delivery of personalized cultural experiences. Specifically, we develop the content and create the application required in order to provide highly personalized visits to the Archaeological Museum in Tripolis, Greece. We also examine the usability issues related to the use of Google Cardboards. Early results are promising, and based on them we also outline the next steps ahead.}, doi = {10.1109/smap.2017.8022676}, url = {https://ieeexplore.ieee.org/document/8022676/}, author = {Marinos Theodorakopoulos and Nikos Papageorgopoulos and Andriana Mourti and Angela Antoniou and Manolis Wallace and Giorgos Lepouras and Costas Vassilakis and Nikos Platis} } @article {vassilakis-snam-2017a, title = {Stimulation of reflection and discussion in museum visits through the use of social media}, journal = {Social Network Analysis and Mining}, volume = {7}, number = {40}, year = {2017}, month = {12}, pages = {1-12}, publisher = {Springer-Verlag GmbH Austria}, abstract = {In this paper, we examine how social media can be linked to cultural heritage and in particular how we can incorporate games, social networks, history reflection and culture. More specifically, we explore the following aspects: (a) how social media sites can be integrated into the museum user experience (b) how user interactions within the social media, both within the context of the museum experience and outside it, can be exploited to enhance the quality of recommendations made to the users, (c) how trending topics from social media can be used to link museum exhibits with today{\textquoteright}s topics of interest and (d) how multi-level related terms extraction from social media data can lead to proposals for reflections to users. The end goal is to provide increased stimuli for users to study exhibits deeper and reflect on them, as well as to trigger discussion between the users, thus maximizing the impact of a museum visit.}, keywords = {big data, cognitive style, Communication, reflection, Social Networks, user profiling}, doi = {10.1007/s13278-017-0460-3}, url = {https://link.springer.com/article/10.1007/s13278-017-0460-3}, author = {Costas Vassilakis and Angela Antoniou and Giorgos Lepouras and Vassilis Poulopoulos and Manolis Wallace and Stavroula Bampatzia and Ioannis Bourlakos} } @proceedings {DBLP:conf/edbt/2016w, title = {Proceedings of the Workshops of the EDBT/ICDT 2016 Joint Conference, EDBT/ICDT Workshops 2016, Bordeaux, France, March 15, 2016}, volume = {1558}, year = {2016}, publisher = {CEUR-WS.org}, url = {http://ceur-ws.org/Vol-1558}, editor = {Themis Palpanas and Kostas Stefanidis} } @proceedings {DBLP:conf/esws/2016, title = {The Semantic Web. Latest Advances and New Domains - 13th International Conference, ESWC 2016, Heraklion, Crete, Greece, May 29 - June 2, 2016, Proceedings}, volume = {9678}, year = {2016}, publisher = {Springer}, isbn = {978-3-319-34128-6}, doi = {10.1007/978-3-319-34129-3}, url = {https://doi.org/10.1007/978-3-319-34129-3}, editor = {Harald Sack and Eva Blomqvist and Mathieu d{\textquoteright}Aquin and Chiara Ghidini and Simone Paolo Ponzetto and Christoph Lange} } @conference {570, title = {Constructing Subsumption Hierarchies of Web Queries}, booktitle = {Proceedings of the International Workshop on Dataset PROFIling and fEderated Search for Linked Data (PROFILES @ ESWC)}, year = {2015}, month = {May}, address = {Portoroz, Slovenia}, author = {Alexander Prohaska and Christos Tryfonopoulos and Georgiana Ifrim} } @conference {kmas15, title = {A mobile-enabled platform for presenting and disseminating cultural heritage information enhanced with augmented reality (Greek title: ΜΙΑ ΠΛΑΤΦΟΡΜΑ ΓΙΑ ΠΑΡΟΥΣΙΑΣΗ ΚΑΙ ΔΙΑΧΥΣΗ ΠΛΗΡΟΦΟΡΙΩΝ ΠΟΛΙΤΙΣΤΙΚΗΣ ΚΛΗΡΟΝΟΜΙΑΣ ΜΕ ΥΠΟΣΤΗΡΙΞΗ ΓΙΑ ΚΙΝΗΤΕΣ ΣΥΣΚΕΥΕΣ ΚΑΙ ΕΜΠ}, booktitle = {1st Panhellenic Conference on Cultural Heritage Digitization}, year = {2015}, month = {9}, abstract = {The advent of mobile technologies has created opportunities for more effective delivery of cultural heritage information to all interested parties, and especially tourists who are on-the-move. Many people nowadays are equipped with smartphones or tablets equipped with location tracking devices such as GPS and compasses and having internet access available; these smartphones can be used for efficient delivery of cultural heritage information, in a personalized and timely fashion. Moreover, the computing resources of these smartphones are adequate to enable the use of augmented reality techniques, which provide a lively and engaging experience to the users. However, the same content still needs to be disseminated to users of stationary computers. In this paper, we report on the design and development of a mobile-enabled platform for presenting and disseminating cultural heritage information enhanced with augmented reality and integration with social networks.}, author = {K. Μασσέλος and Costas Vassilakis and Giorgos Lepouras and Christos Tryfonopoulos and Ν. Τσελίκας and Nikos Platis} } @conference {556, title = {A Platform for the Presentation and Dissemination of Cultural Heritage Information for Mobile Devices Enriched with Augmented Reality}, booktitle = {Proceedings of the Greek Conference for the Digitization of Cultural Information (EUROMED)}, year = {2015}, month = {September}, address = {Volos, Greece}, author = {K. Masselos and Costas Vassilakis and Giorgos Lepouras and Christos Tryfonopoulos and N. Tselikas and N. Platis} } @conference {aamas15-GPT, title = {PViz: Visualising P2P Multi-Agent Simulations}, booktitle = {Proceedings of the International Conference on Autonomous Agents and Multiagent Systems (AAMAS)}, year = {2015}, month = {May}, pages = {1945{\textendash}1946}, address = {Istanbul, Turkey}, author = {Dimitris Giouroukis and Nikos Platis and Christos Tryfonopoulos} } @inbook {565, title = {SECRETA: A Tool for Anonymizing Relational, Transaction and RT-Datasets}, booktitle = {Medical Data Privacy Handbook}, year = {2015}, pages = {83-109}, publisher = {Springer}, organization = {Springer}, author = {Giorgos Poulis and Aris Gkoulalas-Divanis and Grigorios Loukides and Spiros Skiadopoulos and Christos Tryfonopoulos}, editor = {Aris Gkoulalas-Divanis and Grigorios Loukides} } @inbook {DBLP:books/sp/15/PoulisGLST15, title = {SECRETA: A Tool for Anonymizing Relational, Transaction and RT-Datasets}, booktitle = {Medical Data Privacy Handbook}, year = {2015}, pages = {83{\textendash}109}, doi = {10.1007/978-3-319-23633-9_5}, url = {https://doi.org/10.1007/978-3-319-23633-9_5}, author = {Giorgos Poulis and Aris Gkoulalas-Divanis and Grigorios Loukides and Spiros Skiadopoulos and Christos Tryfonopoulos} } @article {DBLP:journals/tdp/PoulisSLG14, title = {Apriori-based algorithms for k\(^\mboxm\)-anonymizing trajectory data}, journal = {Trans. Data Privacy}, volume = {7}, number = {2}, year = {2014}, pages = {165{\textendash}194}, url = {http://www.tdp.cat/issues11/abs.a194a14.php}, author = {Giorgos Poulis and Spiros Skiadopoulos and Grigorios Loukides and Aris Gkoulalas-Divanis} } @conference {DBLP:conf/edbt/PoulisGLST14, title = {SECRETA: A System for Evaluating and Comparing RElational and Transaction Anonymization algorithms}, booktitle = {Proceedings of the 17th International Conference on Extending Database Technology, EDBT 2014, Athens, Greece}, year = {2014}, month = {March 24-28}, pages = {620{\textendash}623}, doi = {10.5441/002/edbt.2014.58}, url = {https://doi.org/10.5441/002/edbt.2014.58}, author = {Giorgos Poulis and Aris Gkoulalas-Divanis and Grigorios Loukides and Spiros Skiadopoulos and Christos Tryfonopoulos} } @conference {lep14a, title = {Towards a Learning Analytics Platform for Supporting the Educational Process}, booktitle = {Proceedings of the 5th Conference on Information, Intelligence, Systems \& Application (IISA2014)}, year = {2014}, month = {7}, abstract = {In this paper, we present the vision of an open source learning analytics platform, able to harvest data from different sources, including e-learning platforms and environments, registrar{\textquoteright}s information systems, alumni systems, etc., so as to provide all stakeholders with the necessary functionality to make decisions on the learning process. The platform{\textquoteright}s architecture is modular, allowing the introduction of new functionality or connection to new systems to collect needed data. All data can be analyzed and presented though interactive visualizations to find correlations between metrics, to make predictions for students or student groups, to identify best practices for instructors and let them explore {\textquoteright}what-if{\textquoteright} scenarios, to offer students personalized recommendations and personalized detailed feedback, etc. Our objective is to inform and empower all stakeholders to improve the learning experience.}, doi = {10.1109/IISA.2014.6878750}, url = {http://ieeexplore.ieee.org/document/6878750/}, author = {Giorgos Lepouras and Akrivi Katifori and Costas Vassilakis and Angela Antoniou and Nikos Platis} } @conference {DBLP:conf/pkdd/PoulisLGS13, title = {Anonymizing Data with Relational and Transaction Attributes}, booktitle = {Machine Learning and Knowledge Discovery in Databases - European Conference, ECML PKDD 2013, Prague, Czech Republic, September 23-27, 2013, Proceedings, Part III}, year = {2013}, pages = {353{\textendash}369}, doi = {10.1007/978-3-642-40994-3_23}, url = {https://doi.org/10.1007/978-3-642-40994-3_23}, author = {Giorgos Poulis and Grigorios Loukides and Aris Gkoulalas-Divanis and Spiros Skiadopoulos} } @conference {DBLP:conf/mdm/PoulisSLG13, title = {Distance-Based k\^m-Anonymization of Trajectory Data}, booktitle = {2013 IEEE 14th International Conference on Mobile Data Management, Milan, Italy, June 3-6, 2013 - Volume 2}, year = {2013}, pages = {57{\textendash}62}, doi = {10.1109/MDM.2013.66}, url = {https://doi.org/10.1109/MDM.2013.66}, author = {Giorgos Poulis and Spiros Skiadopoulos and Grigorios Loukides and Aris Gkoulalas-Divanis} } @conference {550, title = {DS4: A Distributed Social and Semantic Search System}, booktitle = {Proceedings of 35th European Conference on Information Retrieval (ECIR)}, year = {2013}, month = {March}, address = {Moscow, Russia}, author = {Dionisis Kontominas and Paraskevi Raftopoulou and Christos Tryfonopoulos and E.G.M. Petrakis} } @conference {539, title = {DS4: Introducing Semantic Friendship in Distributed Social Networks.}, booktitle = {Proceedings of the 21st International Conference on Cooperative Information Systems (CoopIS)}, year = {2013}, month = {September}, address = {Graz, Austria}, author = {Paraskevi Raftopoulou and Christos Tryfonopoulos and E.G.M. Petrakis and Nikos Zevlis} } @article {DBLP:journals/corr/ZervakisTPKS13, title = {Full-text Support for Publish/Subscribe Ontology Systems}, journal = {CoRR}, volume = {abs/1307.2015}, year = {2013}, url = {http://arxiv.org/abs/1307.2015}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos} } @conference {DBLP:conf/icdm/PoulisSLG13, title = {Select-Organize-Anonymize: A Framework for Trajectory Data Anonymization}, booktitle = {13th IEEE International Conference on Data Mining Workshops, ICDM Workshops, TX, USA, December 7-10, 2013}, year = {2013}, pages = {867{\textendash}874}, doi = {10.1109/ICDMW.2013.136}, url = {https://doi.org/10.1109/ICDMW.2013.136}, author = {Giorgos Poulis and Spiros Skiadopoulos and Grigorios Loukides and Aris Gkoulalas-Divanis} } @conference {554, title = {Full-text Support for Publish/Subscribe Ontology Systems}, booktitle = {Proceedings of the Extended Semantic Web Conference (ESWC)}, year = {2012}, month = {May}, address = {Crete, Greece}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos} } @article {lyk11a, title = {Wikis in enterprise settings: a survey}, journal = {Enterprise Information Systems}, volume = {6}, number = {1}, year = {2012}, month = {feb}, pages = {1-53}, publisher = {Informa UK Limited}, abstract = {The wiki technology is increasingly being used in corporate environments to facilitate a broad range of tasks. This survey examines the use of wikis on a variety of organisational tasks that include the codification of explicit and tacit organisational knowledge and the formulation of corporate communities of practice, as well as more specific processes such as the collaborative information systems development, the interactions of the enterprise with third parties, management activities and organisational response in crisis situations. For each one of the aforementioned corporate functions, the study examines the findings of related research literature to highlight the advantages and concerns raised by the wiki usage and to identify specific solutions addressing them. Finally, based on the above findings, the study discusses various aspects of the wiki usage in the enterprise and identifies trends and future research directions on the field.}, doi = {10.1080/17517575.2011.580008}, url = {http://dx.doi.org/10.1080/17517575.2011.580008}, author = {Ioanna Lykourentzou and Foteini Dagka and Katerina Papadaki and Giorgos Lepouras and Costas Vassilakis} } @conference {wallace11a, title = {Supporting User Roles in Ontology Fuzzification}, booktitle = {Proceedings of the 6th International Workshop on Semantic media adaptation and personalization (SMAP)}, year = {2011}, month = {dec}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, abstract = {Manual ontology development is clearly a strenuous task. Whilst a variety of ontological engineering methodologies exist, their actual application is far from trivial, mainly due to the widely diverse nature of the tasks involved. In this work we study these tasks and identify the different types of human experts that are best suited to perform each one. As a result, we present a cooperative version of an ontological engineering methodology, together with a graphical tool that supports it.}, keywords = {domain expert, fuzzification, knowledge engineer, ontology development, user roles}, doi = {10.1109/smap.2011.24}, url = {https://www.computer.org/csdl/proceedings/smap/2011/4524/00/4524a057.pdf}, author = {Manolis Wallace and Panos Alexopoulos and Ioannis Papafragkos and Costas Vassilakis} } @article {dix2010b, title = {From the web of data to a world of action}, journal = {Journal of Web Semantics}, volume = {8 issue 4}, year = {2010}, pages = {394-408}, abstract = {This paper takes as its premise that the web is a place of action, not just information, and that the purpose of global data is to serve human needs. The paper presents several component technologies, which together work towards a vision where many small micro-applications can be threaded together using automated assistance to enable a unified and rich interaction. These technologies include data detector technology to enable any text to become a start point of semantic interaction; annotations for web-based services so that they can link data to potential actions; spreading activation over personal ontologies, to allow modelling of context; algorithms for automatically inferring {\textquoteleft}typing{\textquoteright} of web-form input data based on previous user inputs; and early work on inferring task structures from action traces. Some of these have already been integrated within an experimental web-based (extended) bookmarking tool, Snip!t, and a prototype desktop application On Time, and the paper discusses how the components could be more fully, yet more openly, linked in terms of both architecture and interaction. As well as contributing to the goal of an action and activity-focused web, the work also exposes a number of broader issues, theoretical, practical, social and economic, for the Semantic Web.}, doi = {10.1016/j.websem.2010.04.007}, author = {Alan Dix and Giorgos Lepouras and Akrivi Katifori and Costas Vassilakis and Tiziana Catarci and Antonella Poggi and Yannis Ioannidis and Miguel Morae and I. Daradimos and Nazihah Md.Akima and Shah Rukh Humayound and Fabio Terella} } @conference {594, title = {Peer Rewiring in Semantic Overlay Networks under Churn}, booktitle = {Proceedings of the 18th International Conference on Cooperative Information Systems (CoopIS)}, year = {2010}, month = {October}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Crete, Greece}, abstract = {Semantic overlay networks have been proposed as a way to organise peer-to-peer networks; peers that are semantically, thematically or socially similar are discovered and logically organised into groups. Efficient content retrieval is then performed by routing the query towards peer groups based on their likelihood to match the query. In this paper, we study the behaviour of semantic overlay networks that support full- fledged information retrieval in the presence of peer churn. We adopt a model for peer churn, and study the effect of network dynamics on peer organisation and retrieval performance. The overlay network is evaluated on a realistic peer-to-peer environment using real-world data and queries, and taking into account the dynamics of user-driven peer participation. Using this evaluation, we draw conclusions on the performance of the system in terms of clustering efficiency, communication load and retrieval accuracy in such a realistic setting.}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis} } @article {540, title = {Rewiring Strategies for Semantic Overlay Networks}, journal = {Distributed and Parallel Databases (DAPD)}, volume = {26}, year = {2009}, pages = {181{\textendash}205}, abstract = {Semantic overlay networks cluster peers that are semantically, thematically or socially close into groups, by means of a rewiring procedure that is periodically executed by each peer. This procedure establishes new connections to similar peers and disregards connections to peers that are dissimilar. Retrieval effectiveness is then improved by exploiting this information at query time (as queries may address clusters of similar peers). Although all systems based on semantic overlay networks apply some rewiring technique, there is no comprehensive study showing the effect of rewiring on system{\textquoteright}s performance. In this work, a framework for studying the attribution of rewiring strategies in semantic overlay networks is proposed. A generic approach to rewiring is presented and several variants of this approach are reviewed and evaluated. We show how peer organisation is affected by the different design choices of the rewiring mechanism and how these choices affect the performance of the system overall (both in terms of communication overhead and retrieval effectiveness). Our experimental evaluation with real-word data and queries confirms the dependence between rewiring strategies and retrieval performance, and gives insights on the trade-offs involved in the selection of a rewiring strategy.}, keywords = {Information retrieval, peer-to-peer networks, rewiring strategies, semantic overlay networks}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis and Christos Tryfonopoulos} } @conference {595, title = {iCluster: a Self-Organizing Overlay Network for P2P Information Retrieval}, booktitle = {Proceedings of 30th European Conference on Information Retrieval (ECIR)}, year = {2008}, month = {March}, address = {Glasgow, Scotland}, abstract = {We present iCluster, a self-organizing peer-to-peer overlay network for supporting full-fledged information retrieval in a dynamic environment. iCluster works by organizing peers sharing common interests into clusters and by exploiting clustering information at query time for achieving low network traffic and high recall. We define the criteria for peer similarity and peer selection, and we present the protocols for organizing the peers into clusters and for searching within the clustered organization of peers. iCluster is evaluated on a realistic peer-to-peer environment using real-world data and queries. The results demonstrate significant performance improvements (in terms of clustering efficiency, communication load and retrieval accuracy) over a state-of-the-art peer- to-peer clustering method. Compared to exhaustive search by flooding, iCluster exchanged a small loss in retrieval accuracy for much less message flow.}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis} } @conference {549, title = {Information Retrieval and Filtering over Self-Organising Digital Libraries}, booktitle = {Proceedings of the 12th European Conference on Research and Advanced Technology for Digital Libraries (ECDL)}, year = {2008}, month = {September}, address = {Aarhus, Denmark}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis and Christos Tryfonopoulos and Gerhard Weikum} } @conference {596, title = {A Measure for Cluster Cohesion in Semantic Overlay Networks}, booktitle = {Proceedings of the 6th International Workshop on Large-Scale Distributed Systems for Information Retrieval (LSDS-IR)}, year = {2008}, month = {October}, publisher = {ACM}, organization = {ACM}, address = {Napa Valley, California}, abstract = {Semantic overlay networks cluster peers that are semantically, thematically or socially close into groups by means of a rewiring procedure that is periodically executed by each peer. Rewiring proceeds by establishing new connections to similar peers, and by discarding connections that are out- dated or pointing to dissimilar peers. This process aims at improving cluster quality (how well peers with similar con- tent are clustered together) and by this, at improving the flow of information in the network by reducing the number of messages that are exchanged. Therefore, measuring the quality of clustering is an important issue by itself. This is exactly the issue this work is dealing with. In this paper, we introduce a new clustering measure that takes into account the whole neighbourhood of a peer (rather than its direct neighbours) thus, providing better insight on the quality of the underlying clustered organisation. Our experimental evaluation with real-word data and queries confirms our assumption that the new measure is better suited for measuring clustering quality than other known measures, such as the (generalised) clustering coefficient.}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis} } @article {DBLP:journals/tkde/PolyzotisSVSF08, title = {Meshing Streaming Updates with Persistent Data in an Active Data Warehouse}, journal = {IEEE Trans. Knowl. Data Eng.}, volume = {20}, number = {7}, year = {2008}, pages = {976{\textendash}991}, doi = {10.1109/TKDE.2008.27}, url = {https://doi.org/10.1109/TKDE.2008.27}, author = {Neoklis Polyzotis and Spiros Skiadopoulos and Panos Vassiliadis and Alkis Simitsis and Nils-Erik Frantzell} } @conference {Katifori2008a1, title = {Personal Ontology Creation and Visualization for a Personal Interaction Management System}, booktitle = {Proceedings of PIM, CHI 2008}, year = {2008}, month = {4}, abstract = {Ontologies offer a flexible and expressive layer of abstraction, very useful for capturing the semantics of information repositories and facilitating their retrieval either by the user or by the system to support user tasks. This work presents an ontology-based user profiler, in the context of a Personal Interaction Management System (PIMS). The profiler, based on an ontology of the users? domain, enables them to create their personal ontology by initially choosing one of the available template ontologies as a starting point, which they subsequently populate and customize. The profiler employs a web interface which allows users to populate their personal ontology through forms, hiding ontology complexities and peculiarities. Forms are dynamically generated through ontology views, which are specified by ontology designers.}, author = {Akrivi Katifori and Costas Vassilakis and I. Daradimos and Giorgos Lepouras and Yannis Ioannidis and Alan Dix and Antonella Poggi and Tiziana Catarci} } @proceedings {DBLP:conf/ssd/2007, title = {Advances in Spatial and Temporal Databases, 10th International Symposium, SSTD 2007, Boston, MA, USA, July 16-18, 2007, Proceedings}, volume = {4605}, year = {2007}, publisher = {Springer}, isbn = {978-3-540-73539-7}, doi = {10.1007/978-3-540-73540-3}, url = {https://doi.org/10.1007/978-3-540-73540-3}, editor = {Dimitris Papadias and Donghui Zhang and George Kollios} } @proceedings {DBLP:conf/www/2007, title = {Proceedings of the 16th International Conference on World Wide Web, WWW 2007, Banff, Alberta, Canada, May 8-12, 2007}, year = {2007}, publisher = {ACM}, isbn = {978-1-59593-654-7}, editor = {Carey L. Williamson and Mary Ellen Zurko and Peter F. Patel-Schneider and Prashant J. Shenoy} } @conference {DBLP:conf/icde/PolyzotisSVSF07, title = {Supporting Streaming Updates in an Active Data Warehouse}, booktitle = {Proceedings of the 23rd International Conference on Data Engineering, ICDE 2007, The Marmara Hotel, Istanbul, Turkey, April 15-20, 2007}, year = {2007}, pages = {476{\textendash}485}, doi = {10.1109/ICDE.2007.367893}, url = {https://doi.org/10.1109/ICDE.2007.367893}, author = {Neoklis Polyzotis and Spiros Skiadopoulos and Panos Vassiliadis and Alkis Simitsis and Nils-Erik Frantzell} } @conference {597, title = {Design and Evaluation of Semantic Similarity Measures for Concepts Stemming from the Same or Different Ontologies}, booktitle = {Proceedings of the 4th Workshop on Multimedia Semantics (WMS)}, year = {2006}, month = {June}, address = {Chania, Crete, Greece}, abstract = {Semantic Similarity relates to computing the similarity between concepts (terms) which are not necessarily lexically similar. We investigate approaches to computing semantic similarity by mapping terms to an ontology and by examining their relationships in that ontology. More specifically, we investigate approaches to computing the semantic similarity between natural language terms (using WordNet as the underlying reference ontology) and between medical terms (using the MeSH ontology of medical and biomedical terms). The most popular semantic similarity methods are implemented and evaluated using WordNet and MeSH. The focus of this work is also on cross ontology methods which are capable of computing the semantic similarity between terms stemming from different ontologies (WordNet and MeSH in this work). This is a far more difficult problem (than the single ontology one referred to above) which has not been investigated adequately in the literature. X-Similarity, a novel cross-ontology similarity method is also a contribution of this work. All methods examined in this work are integrated into a semantic similarity system which is accessible on the Web.}, author = {E.G.M. Petrakis and Giannis Varelas and Angelos Hliaoutakis and Paraskevi Raftopoulou} } @article {592, title = {X-Similarity: Computing Semantic Similarity between Concepts from Different Ontologies}, journal = {Journal of Digital Information Management (JDIM)}, year = {2006}, month = {December}, abstract = {Semantic Similarity relates to computing the similarity between concepts (terms) which are not necessarily lexically similar. We investigate approaches to computing semantic similarity by mapping terms to an ontology and by examining their relationships in that ontology. More specifically, we investigate approaches to computing the semantic similarity between natural language terms (using WordNet as the underlying reference ontology) and between medical terms (using the MeSH ontology of medical and biomedical terms). The most popular semantic similarity methods are implemented and evaluated using WordNet and MeSH. The focus of this work is also on cross ontology methods which are capable of computing the semantic similarity between terms stemming from different ontologies (WordNet and MeSH in this work). This is a far more difficult problem (than the single ontology one referred to above) which has not been investigated adequately in the literature. X-Similarity, a novel cross-ontology similarity method is also a contribution of this work. All methods examined in this work are integrated into a semantic similarity system which is accessible on the Web.}, author = {E.G.M. Petrakis and Giannis Varelas and Angelos Hliaoutakis and Paraskevi Raftopoulou} } @proceedings {DBLP:conf/er/2005, title = {Conceptual Modeling - ER 2005, 24th International Conference on Conceptual Modeling, Klagenfurt, Austria, October 24-28, 2005, Proceedings}, volume = {3716}, year = {2005}, publisher = {Springer}, isbn = {3-540-29389-2}, doi = {10.1007/11568322}, url = {https://doi.org/10.1007/11568322}, editor = {Lois M. L. Delcambre and Christian Kop and Heinrich C. Mayr and John Mylopoulos and Oscar Pastor} } @conference {598, title = {Semantic Similarity Methods in WordNet and their Application to Information Retrieval on the Web}, booktitle = {Proceedings of 7th ACM International Workshop on Web Information and Data Management (WIDM)}, year = {2005}, month = {November}, publisher = {ACM}, organization = {ACM}, address = {Bremen, Germany}, abstract = {Semantic Similarity relates to computing the similarity be- tween concepts which are not lexicographically similar. We investigate approaches to computing semantic similarity by mapping terms (concepts) to an ontology and by examining their relationships in that ontology. Some of the most popular semantic similarity methods are implemented and evaluated using WordNet as the underlying reference ontology. Building upon the idea of semantic similarity, a novel information retrieval method is also proposed. This method is capable of detecting similarities between documents containing semantically similar but not necessarily lexicographically similar terms. The proposed method has been evaluated in retrieval of images and documents on the Web. The experimental results demonstrated very promising performance improvements over state-of-the-art information retrieval methods.}, keywords = {Information retrieval, Semantic Similarity, WordNet, World Wide Web}, author = {Giannis Varelas and Epimenides Voutsakis and Paraskevi Raftopoulou and E.G.M. Petrakis and Evangelos Milios} } @proceedings {DBLP:conf/edbt/2004, title = {Advances in Database Technology - EDBT 2004, 9th International Conference on Extending Database Technology, Heraklion, Crete, Greece, March 14-18, 2004, Proceedings}, volume = {2992}, year = {2004}, publisher = {Springer}, isbn = {3-540-21200-0}, doi = {10.1007/b95855}, url = {https://doi.org/10.1007/b95855}, editor = {Elisa Bertino and Stavros Christodoulakis and Dimitris Plexousakis and Vassilis Christophides and Manolis Koubarakis and Klemens B{\"o}hm and Elena Ferrari} } @proceedings {DBLP:conf/chorochronos/2003, title = {Spatio-Temporal Databases: The CHOROCHRONOS Approach}, volume = {2520}, year = {2003}, publisher = {Springer}, isbn = {3-540-40552-6}, doi = {10.1007/b83622}, url = {https://doi.org/10.1007/b83622}, editor = {Manolis Koubarakis and Timos K. Sellis and Andrew U. Frank and St{\'e}phane Grumbach and Ralf Hartmut G{\"u}ting and Christian S. Jensen and Nikos A. Lorentzos and Yannis Manolopoulos and Enrico Nardelli and Barbara Pernici and Hans-J{\"o}rg Schek and Michel Scholl and Babis Theodoulidis and Nectaria Tryfona} } @proceedings {DBLP:conf/caise/2002, title = {Advanced Information Systems Engineering, 14th International Conference, CAiSE 2002, Toronto, Canada, May 27-31, 2002, Proceedings}, volume = {2348}, year = {2002}, publisher = {Springer}, isbn = {3-540-43738-X}, doi = {10.1007/3-540-47961-9}, url = {https://doi.org/10.1007/3-540-47961-9}, editor = {Anne Banks Pidduck and John Mylopoulos and Carson C. Woo and M. Tamer {\"O}zsu} } @conference {1993-kassapidis-hci, title = {Comparative Study of Protocols of the Transport Layer for Multimedia Applications}, booktitle = {Proceedings of the 4th Hellenic Conference on Informatics}, year = {1993}, month = {12}, pages = {105-118}, abstract = {The forthcoming use of multimedia applications will require powerful computers and high performance networks. While great progress has been made to the physical layer of networks, the upper software layers of the OSI reference model have not kept up pace with them. This paper presents the demands imposed by multimedia applications on the underlying networks and their mapping to transport layer services, that protocols implementing it must provide. Four well-known transport layer protocols are briefly presented (TCP, TP4, VMTP, HSTP/XTP). The mechanisms employed by each one of those are studied and their suitability for demanding multimedia environments are evaluated. We conclude that much more effort needs to be made on the transport layer protocols so that high performance network architectures will be available to fullfill the diverse requirements of tomorrow{\textquoteright}s multimedia applications.}, url = {http://cst.uop.gr/images/papers/1993-kassapidis-hci.pdf}, author = {Kassapidis, P. and Costas Vassilakis and M. Nikolaidou and P. Georgiadis and Votsis, Gr. and Pronios, N.} }